Combination momentary maintained switch



Feb, 3, 1959 c. H. THOMPSON 2,872,542

COMBINATION MOMENTARY MAINTAINED SWITCH Filed April 29, 1958 Tg3 El.; 5745 6292 936s .v 40 36 7G E- INVENTOR.

CLAYTON H. THOMPSON .I BY

ATTORNEYS COMBINATIDN MMENTARY MAIN TAINED SWITCH Clayton H. Thompson,Elgin, lll. Application April 29, 1958, Serial No. 731,834 Claims. (Cl.20G-86.5)

This invention relates to foot switches, and more particularly to animproved foot switch with a control means integrally embodied therewith.

Certain situations are frequently found by doctors, nurses andassistants in hospitals, as well as other operators in industry, that itis desirable to control a plurality of electrical circuits inpredetermined arrangement by the use of foot switches. ln some suchinstances it is necessary to employ a separate foot switch for theoperation of each circuit. This practice creates a problem of fatigueand error as well as time delay.

It is therefore an object of this invention to provide a singlecombination momentary maintained foot switch of improved and noveldesign having a multi-position treadle and latching bars by which aplurality of electrical circuits may be controlled in a predeterminedmanner.

It is a further object of this invention to provide in a foot switch andcontrol means permitting the operator to place the switch upon the flooradjacent a device to be electrically controlled, arranging it in thedesired operative position whereby the foot of the operator may beplaced thereon in a simple and easy manner and oscillated withoutvisually observing the switch.

It is another object of this invention to provide in a foot switch withcontrol means to allow the foot of an operator to remain uponthe'treadle and be freely oscillated between a plurality cf positionsfor effecting the control of a plurality of electrical circuits, orallow thetreadle to be moved by the foot in one direction to operate oneelectrical circuit, the treadle remaining in locked position even withthe foot removed, until the treadle is again actuated by the foot andmoved to another location.

Another object of this invention is to provide a foot switch and controltherewith of the above type referred to which can be easily, quietly,and quickly converted from oscillating non-latching operation bydownward pressure of the operators foot, or converted into latchingposition eifecting control of an electrical circuit by side movement ofthe operators foot before removal from the switch.

Another object of this invention is to provide a foot switch and manualcontrol which lends itself to assembly and use in hazardous locationswhich require explosionproof equipment due to use of explosive vaporsand explosive gases thereabout.

Other objects, and objects relating to details of construction andeconomies of manufacture will appear as in the following description ofthe embodiments ofthe invention which, for the purposes of the presentapplica` tion, is illustrated in the accompanying drawings, in which:

Figure 1 is a top plan view of an electrical switch and control embodiedtherewith embodying the features of this invention;

Figure 2 is a plan View of the electrical switch and ited States Patent0 control means shown by Fig. l with the top cover, or treadle removed;

Figure 3 is a transverse sectional view taken along line III- Ill ofFigure 2 showing the switch mechanism;

Figure 4 is a transverse sectional view taken along line IV-IV of Figure2 showing the control mechanism;

Figure 5 is an end elevational view of the device shown in Fig. l, theactuator being shown in section and the treadle in vits initial inactivelocation;

Figure 6 is a view of the device shown in Figure 5 but having thetreadle shown in one of its active locationsand latched in saidlocation.

Figure 7 is an enlarged partial transverse sectional view of the partsshown in Figure 4, the control parts being shown in the location asshown by Figure 6, the treadle shown by dotted lines;

Figure 8 is a fragmentary sectional view of the actuator and a portionof the treadle taken substantially on line VIII- VIII of Figure l; and

Figure 9 is a fragmentary sectional view taken substantially on lineX-IX of Figure l.

The features of the invention, although not necessarily so limited, lendthemselves particularly to control means and to a switch of the footpedal type and are, therefore, illustrated by way of example inconnection with such a device.

The switch and control means 10 as illustrated in the figures, includesa housing 11 open at the top and having closed bottom and side walls.The cover, or treadle 25 is pivotally assembled upon the housing 11 foroscillation and eifecting actuation of the switch.

The interior of the housing 11 provides a bottom 24 with a forward area12 and a rearward area 13, the rearward area 13 embodying two snap overtoggle switch mechanisms 14 and 15. arranged parallel with each otherand in longitudinal alignment of the housing, the mechanism duly shownby Patent 2,521,015. Each switch embodies a body portion, a contact pin,an upper metal cover plate and an angular actuating arm pivotallymounted therewith. Said switch 14 embodies a body portion 17, anactuating pin 18, a pivoting plate 19 and an angularly formed actuatingarm 2G, said arm 20 having an angular and elevating member 21 and adepending member 22, said member 21 extending outwardly and upwardlywith regard to the longitudinal center line of the housing. Said switch15 embodies a body portion 27, an actuating pin 28, a pivoting plate 29and an angularly formed actuating arm 3i?, said arm 30 having an angularand elevating member 31 and a depending member 32, said member 31extending outwardly and upwardly with regard to the longitudinal centerline of the housing. A compression serpentine snap-over spring 33 isassembled with and interposed between depending members 22 and 32, saidspring 33 normally biasing the depending arms 22 and 32 towards thebodies 17 and 27 effecting the actuating pins 18 and 28 to move inwardlyinto said body portions 17 andt27 thereby opening the electricalcircuits associated therewith.

The iioor of the bottom 24 has an upwardly extending leg 35 with acircular bore 36 centrally located and adjacent the upper end thereof asshown by Figure 9. The treadle 25 has assembled therewith a rigidangular supporting member with a horizontal portion 38 and depending leg39. A pin 40 is mounted in the lower end portion o-f said leg 39, a freeend of the pin 4) extending horizontally and rearwardly beneath thetreadle 25. The diameter of the pin is slightly smaller than the bore 36in the leg 35. When the ltreadle 25 is assembled with the housing 11 thepin 4@ geraete in a threaded bore centrally located in the forward endWall of the treadle, the screw 42 is provided with a threadless endwhich enters a threadless bore in the forward'end wall of the housing.The'treadle when mounted upon the housing as described is rockable andcapable of oscillating from one side to the other upon pin di) and theend portion of the screw 42. s

The forward area 12 of the housing 11 embodies the control mechanism foroperating the switch related to above. Supporting blocks 43 are arrangedin said area 12. A C shaped plate is assembled uponthe'supportingrblocks 43 with the rearward free ends bent downwardly andforming depending edge portions 51 and 52 spaced to the rear of saidblocks and forming a transverse channel 4d therebetween. A pair ofsliding bars l and d6 are transversely arranged in said transversechannel 44, thev lower edges thereof in sliding contact with the upperfloor of the bottom 24; the upper edges thereof being in sliding contactwith the undersides of the free ends 5l and 52vof the C plate. The bars45 and y46 have outwardly extending ends 47 and i3 with notched portions53 and 54, said notched end, portions normally extending a slightdistance through openings 55 and 56 in the side walls 57 and 58 of thehousing l. The notched end portions normally allow the treadle 25 toassume a horizontal position, the side walls 59 and 6@ of the treadlesubstantially contacting` the upper sides of said notched portions53 and54. A pair of triangular-shaped operating cams 62 and 6d are pivotallymounted with the supporting blocks d3 adjacent the bars 45 and 46. Eachof the cams 62 and 68 are arranged with one lower corner and twoelevated corners, a pin 63 being rigidly secured in the lower corner ofsaid cam 62 and a pin 69 being rigidly secured in the lower corner'ofsaid cam 68. rThe free ends of said pins 63 and 69 are assembled inhorizontal bores formed in the supporting blocks 43. Sub-V stantiallyabove the pins 63 and 69 are provided pins 72 and 73, said pinsextending rearwardly from the cams 62 and 63 and iit into cross grooves74 and 75 in the upper surfaces of said bars 45 and 46. A serpentinetype spring 76 is assembled with and interposed between the inner ends0f the bars 45 and 46, said spring 76 biasing each bar 45 and 46outwardly. The outward movement of the bars is limited by the traveldistance of pins 72 and 73 about the pins 63 and 69 and is furthercontrolled by an actuator S6 arranged. above said cam members 62 and 68.I

The actuator Sil is clearly shown by Figures l, 4, 5, 6, 7 and 8 andparticularly shown by Figure 8. Said actuator Si) consists of a metalmember with a top surface $1, a forward depending leg 82, and anenlarged rear end portion S3. For assembly of the actuator to thetreadle 25, the depending leg 32 is inserted downwardly through atransverse slot Sd, an angular pin 85 is inserted through an aperture 86in the treadle 25 and into a vertical bore 37 in said actuator at therear end thereof, said aperture S6 being arranged to the rear of saidslot S4. The upwardly extending portion of said pin 85 is locked in saidborevl by an Allen Set Screw S8 horizontally arranged in a threaded bore89 extending from, the rear end of said actuator to the vertical bore 87therein.A The horizontal portion 96 of said pin 85 allows rockable andoscillating movement of the actuator but prevents it from beingaccidentally removed from the treadle. ri'he depending leg 82 of theactuator remains within the slot 84 at all periods, however, it has freeoscillation therein. The depending leg 82 has two corners 92 and 93, asshown by Figures 4 and 7. Said corner 92 is always in contact with thetriangular cam member 62. Said corner 93 is always in contact with thetriangular cam member 68. The oscillation ofsaid leg 32 raises onecorner` and lowers the opposite corner, the raising and lowering of saidcorners 92 and 93 effecting the movement d ofY said cams 62 and 68 aswell as bars d5 and 46 biaser by the spring 76.

Vr[he treadle is pivotally mounted by pin d@ within bore 36 of leg 35 atits forward end and by the unthreaded end of screw d2 at its rearwardend. The lower surface of the treadle rests upon the switch elevatingmembers 2l and 3i of actuating arms Ztl and 3d. The lower corners of theleg 82 of the actuator Sti contact the triangular cams 62 and 68. lnnormal position of the treadle 2,5, the 'free ends 47 and 43 of bars d5and preventV the depending sides 59 and 6l) of the treadle from beinglowered or raised. By the application of foot pressure upon the actuatorSil, both cams are rocked downwardly and the bars d5 and d6 are biasedinwardly, allowing free oscillation of the treadle if the foot is rockedto the right, bar d6 stays in its innermost position while bar is biasedoutwardly by the spring 76 since corner 92 of leg 82 is in an elevatedposition. if the foot pressure is withdrawn, as shown by Figure 7, theend 47 of bar d5 will hold the side wall 5g of treadle 25 in elevatedposition, while side wall 6i; thereof is free to pass over the end d8 ofbar d6. Since the forward end of the treadle is pivoted, the member 3iof arm 3i) is depressed, the depending arm 32 is moved inwardly of thehousing thereby allowing the pin 2% to snap outwardly from the body 27of switch mechanism l5. The closing of the electrical circuit in saidswitch mechanism l5 will effect actuation of some movable object, suchas the elevation of an operating table in a hospital. The switch willremain in set position until the actuator Si) is again depressed and thetreadle 25 returned to a normal, substantially horizoital position. Itwill be noted that the operator was not required to hold the treadle inthe active position by keeping his foot thereon, When a secondelectrical circuit is desired to be controlled, the treadle 25 isoscillated to the opposite side upon actuation of the actuator 8d byrocking of' the operators foot to the left. The bar d6 is then biasedoutwardly locking the side wall 6% of the treadle in an elevatedposition, which inturn forced the switch member 21 downwardly, thedepending arm 22 allowing the pin 13 to snap outwardly from the body25.7 of the switch mechanism i4. The treadle holding the switch in saidset position until reset by actuation of the actuator 80. Y

From the above it will be understood that when the control and switchmechanism is attached to a table in a hospital, or the like, theoperator can start the elevation of the table by depression oftheactuator and treadle to one side, the table will continue its upwardtravel until automaticallyrstopped by a` safety switch or by furtheractuation of the treadle. lt is not necessary to retain a foot upon'thetreadle after it is once depressed. Y It isohvious that the aboveinvention provides a single foot Fcontrol and switch mechanism having amultil position treadle and latching means by which a plurality ofelectrical circuits may be controlled.

For simplicity of presentation and description, the switch embodying theinvention has been described and shown in the drawings as a 1B-positionswitch. It will be apparent, however, that a foot switch constructedv inaccordance with the invention may be designed to have more than twoactuated positions by providing addi- Y tional bars and latching means.Y

It is believed that the operation of the` novel foot switch describedherein is apparent from the foregoing description. itV can be seen thatthere has been provided a control for a footswitchV of novelconstruction in which will permit the control of a plurality ofelectrical circuits, the control and switch being of simple and ruggeddesign assuring long and trouble-free service under adverse operatingconditions.

As many changes could be made in the above construetion many apparentlywidely different embodiments asians-a of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in any limited sense.

I claim as my invention:

l. In a foot switch, a bottom housing, a top treadle pivotally mountedupon said housing for oscillation from one side to the other of saidhousing, a pair of switches in said housing, pivotal arms mounted uponeach switch and responsive to the movement of said treadle, spring meansinterposed between said arms for biasing the free ends thereof intocontact with said treadle, and control means for retaining said treadlein one or more inclined oscillated positions, said control 'meansincluding a pair of latch control bars arranged transversely of saidhousing, spring means interposed between adjacent inner ends of saidbars, said bars normally extending beyond the opposite sides of saidhousing and having end portions formed to allow the treadle to assumethere above 'a horizontal inactive switch position, cam means mounted insaid housing adjacent the inner ends of said bars, means on said cammeans for contacting and actuating said bars, and an actuator mountedupon said treadle and having a portion thereof in engagement with saidcam means, said actuator being vertically and rockably mov- `able sothat the depression of the actuator will cause both of said bars to bedrawn inwardly whereby the treadle can be oscillated in either`direction ,and whereby oscillation of the treadle will cause one bar tobe moved inwardly and the other bar to be moved outwardly therebyallowing one side of the treadle to be lowered and the opposite side tobe raised and retained upwardly by said outwardly extending bar, and theinclined treadle retaining one of the switches'in active position andone in inactive position.

2. in a foot switch, a bottom housing, `a top treadle pivotally mountedupon said housing for oscillation from one side to the other of saidhousing, a pair of switches in said housing, pivotal arms with upper andlower free ends mounted upon each switch and responsive to the movementof said treadle, spring means interposed between the lower free ends ofsaid arms for biasing the upper free ends thereof upwardly into contactwith said treadle, and control means for retaining said treadle in oneor more inclined oscillated positions, said control means including apair of latch control bars arranged transversely in said housing, springmeans interposed between the adjacent inner ends of said bars, said barsnormally extending beyond the opposite sides of said housing and havingreduced end portions to allow the treadle to assume a horizontalinactive switch position, cam means pivotally mounted in said housingadjacent the inner ends of said bars, means on said cam means forcontacting and actuating said bars, and an actuator mounted upon saidtreadle and having a depending leg portion thereof in engagementwith'said cam means, said actuator vertically and rockably movable sothat the depression of the actuator will cause both of said bars to bedrawn inwardly whereby the treadle can be oscillated in eitherdirection, and whereby oscillation of the treadle will cause one bar tobe moved inwardly and the other bar to be moved outwardly therebyallowing one side of the treadle to be lowered and the opposite side tobe raised and retained upwardly by said outwardly extending bar, and theinclined treadle retaining one of the switches in active position andone in inactive position.

3. in a foot switch, a bottom housing, a top treadle pivotally mountedupon said housing for oscillation from one side to the other of saidhousing, a pair of switches in said housing, angular pivotal armsmounted between their ends with upper and lower free ends upon eachswitch an-d responsive to the movement of said treadle, spring meansinterposed between the lower free ends of said arms for biasing theupper free ends thereof up- A6 wardly into contact with said treadle,and control means for retaining said treadle in one or more inclinedoscillated positions, said controi means including a pair of latchcontrol bars arranged transversely of said housing, spring meansinterposed between the adjacent inner ends of said bars, said barshaving reduced end portions to allow the treadle to assume a horizontalinactive switch position, a pair of generally triangular shaped camspivotally mounted in the base of said housing adjacent the inner ends ofsaid bars, means on each of said cams for contacting and actuating saidbars, and an actuator mounted upon said treadle and having a portionthereof in engagement with said cams, said actuator vertically androckahly movable so that the depression of the actuator will effect bothof said bars to be drawn inwardly whereby the treadle can be oscillatedin either direction, and whereby oscillation of the treadle will causeone bar to be moved inwardly and the other bar to be moved outwardlythereby allowing one side of the treadle to be lowered and the oppositeside to be raised and retained upwardly by said outwardly extending bar,and the inclined treadle retaining one of the switches in activeposition and one in inactive position.

4. In a foot switch, a bottom housing, a top treadle pivotally mountedupon said housing for oscillation from one side to the other of saidhousing, a pair of switches in said housing, pivotal angular armsmounted between its ends upon each switch and responsive to the movementof said treadle, a spring interposed between the lower free ends of saidarms for biasing the upper free ends thereof upwardly into contact withsaid treadle, and control means for retaining said treadle in one ormore inclined oscillated positions, said control means including a pairof latch control bars in longitudinal alignment and arrangedtransversely of said housing, a spring interposed between the adjacentinner ends of said bars, said bars having notched end portions, a pairof generally triangular shaped cams pivotally mounted at one of itscorners by a pin inserted in a bore in the base of said housing adjacentthe inner ends of said bars, a pin extending from one of the uppercorners of each of said cams for contacting and actuating said bars, andan actuator mounted upon said treadle and having a depending portionthereof in engagement with said cams, said actuator vertically androckably movable so that the depression of the actuator will cause bothof said bars to be drawn inwardly whereby the treadle can be 4oscillatedin either direction, and whereby oscillation of the treadle will causeone bar to be moved inwardly and the yother bar to be moved outwardlythereby allowing one side of the treadle to be lo-wered and the oppositeside to be raised and retained upwardly by said outwardly extending bar,and the inclined treadle retaining one of the switches in activeposition and one in inactive position.

5. In a foot switch and control therefore, a housing, a top treadlepivotally mounted upon said housing for rocking from one side to theother of said housing, a pair of switches in said housing, substantiallyangular pivotal arms mounted upon each switch responsive to the movementof said treadle, said arms pivoted between their ends providing freelower and upper ends, a spring interposed between the lower free ends ofsaid arms for biasing the upper free ends thereof upwardly into contactwith said treadle, and control means for retaining said treadle in oneor more positions, said control means including a pair of latch controlbars in longitudinal alignment and arranged transversely of saidhousing, a spring interposed between the inner ends of said bars, saidbars having notched end portions extending beyond the sides of thehousing and allowing the treadle to assume a horizontal inactive switchposition, a pair of triangular shaped cams pivotally mounted in the baselof said housing adjacent the inner ends of said bars, said cams mountedwith one corner at the bottom with a flat surface and two cornersthereabove, means projecting from each of the inner upper corners ofsaid cams for fitting into grooves in the top surfaces of said bars foractuating said bars, an actuator mounted upon said treadle and having adepending portion thereof in engagement with said cams, said actuatorverticaliy and rockably movable so that4 the depression of the actuatorwillY cause both 4of said bars to be drawn inwardly whereby the treadlecan be oscillate-d in either direction, and whereby oscillation of thetreadle will cause one bar to be moved inwardly and the other bar to bemoved outwardly'thereby allowing one side of the treadle to be loweredand the opposite side to be raised and retained upwardly by saidoutwardly extending bar, and the inclined treadle retaining one of theswitches in active position and Vone in inactive position.

6; A control means integrally assembled with a toot switch, comprising ab ottom housing, a pair of switches in said housing, a top treadlepivotally mounted upon said housing for oscillation from one side to theother of said housing, pivotal angular arms mounted upon each switchresponsive to the movement of said treadle, said arms being pivotedbetween their ends providing free upper and lower ends, a spring meansinterposed between the lower free ends of said arms for biasing theupper free ends thereof upwardly into contact with said treadle, andcontrolV means for retaining said treadle in one or more oscillatedpositions, said control means including latch control bars arrangedtransversely of said housing, spring means interposed between adjacentends of said bars, said bars being constructed to permit the treadle toassume a horizontal inactive switch position on said bottom housing, cammeans mounted in said housing adjacent said inner ends of said bars forcontacting and actuating said bars when actuated, an actuator associatedwith said treadle and having a portion engageable by said cam means,said actuator being vertically and rockably movable so that thedepression of the actuator causes both of said bars to be drawn inwardlywhereby the treadle can be oscillated in either direction, and wherebyoscillation of the treadle will cause one bar to be moved inwardly andthe other bar to be moved outwardly thereby allowing one side of thetreadle to be lowered and the opposite side to be raised and retainedupwardly by said outwardly extending bar, and the treadle thus retainingone of the switches in active position and one in inactive position.

7. In a foot switch, an open upper end housing, a pair.

of switches in said housing, a top treadle pivotally mounted upon saidhousing for covering said housing and -f for oscillation from one sideto the other of said housing, substantially right angie pivotal armsmounted between their ends upon each switch responsive to the movementof said treadle, said arms having free upper and lower ends, a springinterposed between the lower free ends of said arms for biasing theupper free ends thereof upwardly into contact with said treadle, andcontrol means for retaining said treadle in one or more inclinedoscillated positions, said control means including a pair of latchcontrol bars in alignment and arranged transversely of said housing, aspring interposed between the adjacent inner ends of said bars, each ofsaid bars having a groove in its top surface and a notched end portionto allow the treadle to assume a horizontal inactive switch position, apair of cams pivotally mounted upon supporting means in tr e base ofsaid housing adjacent the inner ends of said bars, means extendingrearwardly from each of said cams for iitting into the grooves in saidbars for actuating same, an angular shaped actuator mounted upon saidtreadle having a depending end portion in engagement with said cams,said actuator being vertically and rockably movable so that thedepression of the actuator will cause both of said bars to be drawninwardly whereby the treadle can be oscillated in either direction, andwhereby oscillation of theV treadle will d cause one bar to be movedinwardly and the other bar to be moved outwardly thereby allowing oneside of the treadle to be lowered and the opposite Yside to be raisedand retained upwardly by said outwardly extending bar,

Vand the inclined treadle retainingone `of the switches in activeposition and one in inactive position.

8. A door switch and control device of the character described includinga bottom housing having spaced apart side walls, a front walls, and arear wall, a slotted top treadle pivotally mounted with andlongitudinally of therhousing, said treadle having spaced-apart sidewalls for overlapping the side walls of said housing, a pair of switchesmounted in the rear portion of said housing, a pivotal angular shapedarm mounted upon each switch, arms having upper'and lower free endportions, the app r tree end arm portions in contact with said treadle,a spring interposed between said lower free end portions of said arms,land control means for retaining the treadle in one or morepredetermined locations located in the forward portion of said housing,said control means including a pair of latclied control bars in generalalignment, a spring interposed between` the inner ends of said bars,said bars having their outer ends normally extending beyond the sides ofsaid housing, a pair of cams pivotally mounted in said housing adjacentthe inner ends of said bars, the upper surface of each bar having agroove at the inner end thereof, means on each cam and extendingrearwardly into said groove in a bar, and an actuator mounted upon theupper surface of the Vtreadle and having a depending leg portion thereofextending through the slot in said treadle and in engagement with saidcams, said actuator movable vertically and sideways, the depression ofsaid actuator causing movement of said bars edecting latching ot Athetreadle and switches in contact therewith.

9. An enclosed iioor switch and control device of the characterdescribed including a bottom housing having spaced apart side walls, afront wall, and a rear wail, a top treadle pivotally mounted with andlongitudinally of the housing, said treadle having spaced-apart sidewalls for overlapping the side walls of said housing, a pair of switchesmounted in the rear portion of said housing, a pivotal arm mounted uponeach switch, said arms having upper and lower free end portions, theupper free end arm in contact with said treadle, a spring interposedbetween said lower free end portions, and manual control means forretaining the treadle in one or more predetermined locations located inthe forward portion of said housing, said control means including twocontrol bars arranged in general alignment slidably mounted upon thebase or the housing, a spring interposed between the inner ends of saidbars, said bars having their outer ends normally extending beyond thesides of said housing, a pair of cams pivotally mounted in said housingadjacent the inner ends of said bars, the upper surface of each barhaving a depression at the inner ends thereof, means on each cam andextending rearwardly into said depression in a bar, and an actuatormounted upon the upper surface of the treadle and having a depending legportion thereof extending through said treadle and in engagement withsaid cams, said actuator being movable vertically and sideways, thedepression of said actuator eiecting movement of said bars causinglatching of the treadle and switches in contact therewith.

li). An enclosed floor switch and control device of the characterdescribed including a bottom housing having spaced apartV side weils,aifront wall, and a rear wall, a top treadle, a support member extendingupwardly from the base of said housing, said treadle being pivotallymounted to said support member longitudinally ofthe housing, saidtreadle also being pivotally mounted to the front wall of said housing,said treadle having spaced-apart side walls for overlapping the sidewalls of said housing, a pair of switches including actuating pinsmounted in said housing, pivotal arms mounted upon each switch, Saidarms having upper and lower free end portions, the upper free endportions in contact with the said treadle, the downwardly extending freearm portions in contact with said switch actuating pins, and manualcontrol means for retaining the treadle in one or more predeterminedlocations located in the forward portion of said housing, said controlmeans including two control bars arranged in longitudinal alignmentslidaby mounted upon the base ofthe housing, a spring interposed betweenthe inner ends of said bars, said bars having their outer ends normallyextending beyond the sides of said housing, a pair of cams pivotallymounted in said housing adjacent the inner ends of said bars, a piu oneach cam and extending into engagement with one of said bars, and anactuator mounted upon the upper surface of the treadle and having adepending portion thereof extending through said treadle and inengagement with said cams, said actuator movable vertically andsideways, the depression of said actuator effecting movement of saidbars thus causing latching of the treadle and switches in contacttherewith.

Schneider Apr. 21, 1953 Heidman Oct. 9, 1956

